Chassis for housing telecommunications modules provide a structure for protecting the modules from externalities while providing heat dissipation for circuitry contained on the modules and while shielding the modules from electromagnetic interference. Furthermore, a chassis may be required to control flame spread should a fire ever be imposed within the chassis. In the case of modules that have fiber optic cable connections, the chassis additionally may be required to accommodate and manage fiber cables connected to one or more modules. These fiber cables must maintain a bend radius of greater than a certain amount to prevent fiber breaks and/or signal attenuation.
As the density of modules within a given chassis volume increases, the functions expected of the chassis generally become more difficult to accomplish. The number of heat generating components increases while the spacing between modules decreases. Additionally, a greater number of data signals pass through the chassis presenting a higher signal vulnerability and likelihood of signal cross-talk. Specifically, when the modules have fiber cable connections, the chassis must manage a greater number of cables, and the likelihood of overbending one or more of the cables increases.
Chassis that can accommodate a high density of modules with the ability to convert electrical signals to optical and optical to electrical are useful in various applications. For example, electrical to optical and optical to electrical conversion are useful in applications where signals arrive in electrical media but must be distributed over distances greater than is possible over a continuous electrical conductor. Signals may only be transferred relatively limited distances on electrical conductors due to attenuation before repeaters must be introduced to reconstruct the signal. However, fiber conductors can carry a signal over distances many times greater than electrical conductors. Therefore, applying an electrical to optical conversion for a signal prior to distribution and then optical to electrical conversion near the destination eliminates the need for the interposed repeater circuits. Also, employing one large diameter fiber optic cable reduces the clutter that would result from the many coaxial cables that would be necessary.
Generally, these conversions must be done for a large number of communications channels, as is the case when providing communications within a high-rise building where the electrical to optical conversion occurs at the ground floor and optical signals are distributed to the various floors of the building. In such an environment, it is generally desirable to minimize the clutter of equipment so module density within a chassis may be relatively high. Furthermore, some applications require conversions for one data rate while other applications require conversions at another data rate. Thus, there is a need for chassis and module structures that facilitate a high density of telecommunications circuits, including those performing electrical to optical and optical to electrical conversions at one or more data rates.